Newswise - One of the greatest challenges faced by cancer surgeons is toknow exactly which tissue to remove, or not, while the patient is underanesthesia. A team of surgeons and scientists at University of California,San Diego School of Medicine have developed a new technique that will allowsurgeons to identify during surgery which lymph nodes are cancerous so thathealthy tissue can be saved. The findings will be published in the January15 print edition of Cancer Research.

"This research is significant because it shows real-time intraoperativedetection of cancer metastases in mice," said Quyen T. Nguyen, MD, PhD,associate professor of Head and Neck Surgery at UC San Diego School ofMedicine. "In the future, surgeons will be better able to detect and stagecancer that has spread to the patient's lymph nodes using molecules thatwere designed and developed at UC San Diego."

Lymph nodes, located throughout the body, serve as filters that containimmune cells to fight infection and clean the blood. When cancer cells breakaway from a tumor, the cells can travel through the lymph system and hide inthese tiny organs. Surgeons remove the nodes to determine if a cancer hasspread. However, human nodes, only half a centimeter in size, are difficultto discern among the surrounding tissue during surgery. Furthermore, evenwhen surgeons are able to map the location of the nodes, there is no currenttechnique that indicates whether or not the lymph nodes contain cancer,requiring removal of more lymph nodes than necessary.

"With molecular-targeted imaging, surgeons can avoid unnecessary removal ofhealthy lymph nodes which is better long-term for patients," said Nguyen,director of the facial nerve clinic at UC San Diego Health System. "Therange of the surgeon's visual field is greatly enhanced by a molecular toolthat can help achieve accurate surgical margins and detection of metastasesso that no tumor is left behind."

The fluorescently labeled molecules, known as ratiometric activatablecell-penetrating peptides (RACPP), are injectable. When used in mousemodels, surgeons could see where the cancer had spread with high sensitivityand specificity even when the metastatic sites were only a few millimetersin size.

This form of instant pathology is an improvement over traditional sentinelnode mapping, whereby only the location of the lymph node is detectedwithout gleaning any information on actual cancer involvement.

Current methods for managing prostate cancer and neck squamous cellcarcinoma only reveal the extent of cancer involvement after the patient hasundergone surgical removal of all susceptible lymph nodes.

This new technique will decrease OR time because the surgical team need notwait for pathology reports, decrease time under anesthesia, and decreaseunnecessary surgery on noncancerous lymph nodes.

Nyguyen's earlier research with Nobel Prize winner Roger Tsien, PhD,professor of pharmacology at UC San Diego School of Medicine, showed inanimal models how injectable fluorescent peptides could be used to highlighthard-to-see peripheral nerves, allowing surgeons to avoid them when removingor repairing other tissues.